Spark plug



Nov. 10, 1942. a NOWOSIELSK. 2,301,570

SPARK PLUG Original Filed July 1, 1930 I fiimm vw Jamuwuw INVENTQR EdmrdB-Nowoszelskz.

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ATTORNEY Patented Nov. 10, 1942 SPARK PLUG Edward B. Nowosielski, Bloomfield, N. J., as signor,

by mesne assignments, to Bendix Aviation Corporation, South Bend, Ind, a corporation of Delaware Continuation of application Serial No. 465,176, July 1, 1930. This application November 15, 1934, Serial No. 753,211

6 Claims.

This invention relates toignition systems of internal combustion engines, and particularly to the spark plug and associated phases of the system.

An object of the invention is to provide a novel method of assembling the shielding and current conducting parts of-v the system, and of attaching said parts to the spark plug.

A further object is to provide, in combination with a spark plug, an electrical shield therefor, novelmeans for establishing a good mechanical connection between the ignition cable and the shield, and an eflicient electrical connection between the cable and the high potential electrode of the plug.

Another object is to provide a novel spark plug shield which is both mechanically and electrically strong and is capable of long service under severe conditions of usage, as for example, in aircraft engines.

Still another object is to provide a novel spark plug shield which consists of a minimum number of individual parts so as to simplify manufacture and assembly, and which allows ready removal of one or more of the parts for purposes of inspection and replacement without disturbing the assembly of the remaining parts.

Other objects and advantages of the invention will appear more fully hereinafter from the consideration of the detailed description which follows.

Although only one embodiment of the present invention is described and illustrated in the accompanying drawing, it is to be expressly understood that this drawing is for the purpose of illustration only, and is not to be construed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing:

Fig. 1 is an end view of one embodiment of the present invention;

Fig. 2 is a sectional side view taken on the line 2--2 of Fig. 1;

Fig. 3 is a drawn-out side view of the embodiment of Fig. 1, showing the separate parts thereof and indicating the manner of cooperation therebetween when assembled; and

Fig. 4 is an enlarged sectional view of the cable connector taken on line 4-4 of Fig. 2.

Referring now to the drawing, wherein like reference characters indicate like parts throughout the several views, and particularly to Fig. 2, the shielding means has been illustrated in comtrode 6 to the upper end of which is attached a resilient conductor 1 by means of a claw-like collar 8 which is adapted to make electrical contact with the lug or cable terminal 9, the latter having electrical connection with conductor l0 supplying current to the spark plug in the usual manner. The resilient conductor I may be a coil spring as shown, or any other suitable form of spring conductor. Conductor I0 is, of course, insulated, as indicated at I l. The body portion 12 of the spark plug 5 is threaded as at [3 for engagement with the engine cylinder (not shown) and is provided with the usual flange H which, if the plug is not shielded, contacts with a gasket (not shown) inserted between the flange and the engine cylinder in order to make the joint gas-tight.

The shell which is applied to the plug in order to prevent interference with other sensitive electrical apparatus, as for example radio equipment, is extremely simple in structure. In the form shown, a substantially cylindrical metallic sleeve l5 forms the lower portion of the shield and is adapted to surround the body portion of the spark plug. The sleeve I5 also constitutes means for attaching the shield to the spark plug and for this purpose is, provided with an inwardly turned lip or flange I6 which is adapted to engage the under side of flange H of the plug and it is securely held between said flange and the engine cylinder when the plug is inserted therein. Sleeve I5 is also provided with a yielding upper portion having a plurality of circumferentially spaced longitudinal slits II extending downward from the upper end of said sleeve for substantially half its length. This yielding portion formed by slits l1, together with a circumferential indentation l8 which is formed in sleeve l2 just below its upper end, cooperates with other parts of the shield in a manner later to be described to provide means of rapid and easy assembly and disassembly of the shield structure.

The main metallic portion of the shield, which coacts with sleeve i5 to form the complete shield, is in the form of a cylinder having an enlarged head portion and a boss projecting at right angles to the head portion, said boss being provided with a bore which is adapted to form the entrance for the ignition cable. The lower portion of the cylinder cooperates with sleeve l5 and surrounds the upper portion of the spark plug including electrode 6. The enlarged head portion, as shown, is divided into two parts along a plane passing through the axis of the boss and perpendicular to the axis of the lower portion of the cylinder bination with a spark plug 5 having a center elecand comprise a body member I 9 and a cap memher 29. The lower portion 2| of body member I! is substantially cylindrical in shape and is adapted to telescope within the upper yielding portion of sleeve I5, these parts being so formed, as by stamping, that they may be assembled with a sliding frictional flt, slits II allowing a slight resilient expansion of the upper portion of sleeve ll so as to receive portion 2| of body member I9 and indentation I8 cooperating with a circumierential groove 22 formed in the surface of portion '2I to lock these parts together in a readily breakable frictional connection.

The body member I9 is of larger diameter than its lower cylindrical portion 2I, thus forming the lower half of the head portion which is adapted to rest upon the upper edge of sleeve I5. Pro- ,iecting from the portion I8 is the lower half 23 of the boss previously mentioned, the upper half 28 being integral with cap member 29. The boss thus formed by halves 23 and 24 has an internal diameter sufficiently large to receive an insulating bushing 25 through which the cable II passes. This frictional telescoping engagement between the cylinder and sleeve also allows angular adjustment of the cylinder about the longitudinal axis of the plug so as to avoid the necessity for any sharp bends in the ignition cable, which are conductive to insulation failures. Cap member 29 and body member I9 may be held together by any suitable means such as a strong spring clip 28, general characteristics of which are clearly shown in Fig. l. The internal diameter of the circular portion of clip 28 is slightly less than the exterior diameter of the boss formed by halves 23 and 24 and is adapted to engage a groove 21 formed around said boss, closely adjacent the body and cap members I9 and 29.

The remaining element of the shield consists of a high potential insulating member 28 formed of any suitable material, such as porcelain, which is disposed within a metallic housing formed by the portions 2I, I9-and 20 but entirely disconnected therefrom. The shape of the outer surface of the insulating member 28 corresponds in general to that of the interior of the metallic housing and also comprises a head portion 29 which is enclosed by the body member I9 and the cap member 29. Member 28 is provided with a vertical bore 39 of suflicient diameter to provide adequate clearance for the spark plug and with a horizontal or transverse bore 3i extending through the head portion and intersecting the vertical bore 38 for the reception of the cable I I. The closed end of the bore 3i is threaded as indicated at 32 to provide for mechanical attachment of the lug or cable connector 9 to the insulator head 29, said connector being threaded at 33, and also serving as means by which the ignition cable may be electrically connected to the electrode of the spark plug 5 through the spring member I. If desired, the insulating member 28 may be split through its head portion 29 into two parts along the axis of bore 3i in a manner similar to that in which the metallic casing is divided, but it is preferable that this piece be formed as an integral member, as shown in Fig. 2.

The novel cable terminal 9 is in the form of a lug having a substantially hollow cylindrical portion 34 for the reception of the cable I I which is forced therein and the cylindrical portion pinched, as at 35, to prevent the cable from being pulled out of the lug. Electrical connection is made between the lug 9 and conductor III of the cable I I by means of a-screw member or threaded plug II which is adapted to be screwed into the other end of the lug, said plug terminating in a sharp piercing portion 38 adapted to pierce the stranded conductor III. The ends Ila of the conductor strands are then held firmly against the lug by the shoulders of the plug 35 to further insure against pulling of the cable out of the lug. As indicated in Fig. 2, the threaded portion 33 of the lug is screwed into the threaded portion 32 at the closed end of the bore 3| in the head member 29 of insulator 28 and the cylindrical portion 34 provides a surface for makingan eiiicient electrical connection with the positive or high potential electrode 3 through the spring member I. The outer end of the boss is threaded as at 31 to facilitate the bonding of a cable shield 38 to the spark plug shield. The bonding may be effected by means of a metallic bushing 39 arranged to fit over and to be attached to the cable shield 39. The bushing 39 is provided with a circumferential flange 49 adapted to abut against the insulating bushing 25 and held there-against by means of a nut ll, as shown in Fig. 2, which also forms a secure mechanical and electrical connection between the spark plug shield and the cable shield.

The parts may be assembled as follows: Spark plug 5 is placed within sleeve I5 with flange I4 resting on lip I9 and is then threaded into the engine cylinder block in the usual manner, thus tightly clamping lip I6 between flange I9 and the engine cylinder. Body member I9 of the metallic shield is then placed around spark plug 5 and secured to sleeve I5 by telescoping cylindrical portion 2| within the upper portion of the sleeve and forcing the body member downward until indentation I8 engages groove 22 and the upper edge of sleeve I5 abuts the portion I9. The flexible metallic shield 38 of the ignition cable is then pushed back the required distance to allow the end of the cable to be inserted in bore 3i of the enlarged head portion 29 of the insulating member 28, and the lug 9 is then threaded into the portion 32 at the end of the bore 3i. The member 28 is placed over the top of spark plug 5 and is forced downward until spring 1 of the electrode 6 is compressed and makes contact with lug 9, and the insulating bushing 25 is then resting in the bore of the lower half 23 of the boss. Cap member 20 is then placed over the insulator 28 and completes the metallic shield, spring clip 28 being forced into place in groove 21 from the outer end of the boss. Finally, the bushing 39 is placed so that its flange 49 bears against the insulating bushing 25 and then the nut 4| is screwed tightly in boss 23-44.

There is thus provided a novel shield for spark plugs which may be easily and quickly assembled and disassembled and which is adapted for use with any of the well-known types of spark plugs. The shield is light in weight, relatively inexpensive to manufacture, and comprises a minimum of parts, each of which is easily separable from the others for inspection or replacement. Adequate means are provided for thoroughly insulating the ignition cable and the positive electrode of the spark plug from the metallic parts of the shield, thus providing for electrical shielding without impairing the charge-igniting function of the spark plug.

From actual use of this shield, it has been found that a cooler spark plug is obtained, the large metallic surface offering greater opportunity for dissipation and conduction of heat away from the hotter portions of the spark plug.

The'novel shield disclosed herein permits the ignition cable to enter the shield and to be connected to the spark plug terminal in a horizontal plane and also provides that the head portion of the shield may be rotated about the plug, circumferential slippage taking place between cylindrical portion 2| of the body member l8 and sleeve l5, thus enabling the cable to be adjusted to any angular position and to avoid the necessity for sharp bends therein, which are wellknown to be conducive to insulation failures. The novel manner of mechanically and electrically connecting the cable to the insulator and the spark plug, respectively as proposed by the present invention, is extremely simple and eni- ,cient.

It will be obvious that the invention is not limited to the form described and illustrated in the drawing, but is capable of a variety of mechanical embodiments. For example, the cylindrical portion 2| of the member l9 may telescope over the upper yielding portion of sleeve l instead of within said portion as shown, and it may also be preferable to provide the yielding portion of the readily breakable connectiombetween these elements of the shield in the portion 2| instead of in the sleeve. Similarly, changes may be made in the form, details of construction, and arrangement of the parts, without departing from the spirit of the invention, and reference is therefore to be had to the appended claims for a definition of the limits of th invention.

This application is a continuation of my application No. 465,176, filed July 1, 1930.

What is claimed is:

1. Means for connecting a spark plug electrode and cable comprising in combination, a

terminal having a screw engaging the cable center, a socketed part to receive the cable, a collar engaging the electrode, and a spring abutting said collar at one end and said terminal at the other.

2. Means for connecting a spark plug electrode and cable comprising in combination, a terminal having a screw engaging the cable center, a socketed part to receive the cable, a collar engaging the electrode, a spring abutting said collar at one end and said terminal at the other, means for retaining said terminal in position with respect to said cable and plug, and means for supporting said last named means in operative relationship to the plug.

3. In a radio shield for a spark plug, a metal shell having portions of different diameters, which portions form a circular shoulder therebetween, a body of dielectric material within said shell and removable therefrom at will, said body having a circular shoulder for registry with said first-named circular shoulder, a portion of said dielectric body being apertured to receive a conductor, and metallic contact means integrated with said dielectric body and serving to electrically connect said conductor and plug.

4. In a radio shield for a spark plug, a metal shell having a lateral extension, a body of dielectric material within said shell and removable therefrom at will, a portion of said dielectric body aligning with said lateral extension of the shell being apertured to receive a conductor, and metallic contact means for electrically connecting said conductor and plug and including one part to physically engage the conductor and receive ignition current therefrom, and a second part gripping the conductor to hold it against axial displacement,

5. In a radio shield for a spark plug, a metal shell having portions of different diameters, which portions form a circular shoulder therebetween, a body of dielectric material within said shell and removable therefrom at will, said body having a circular shoulder for registry with said first-named circular shoulder, a portion of said dielectric body being apertured to receive a conductor, and metallic contact means for electrical- 1y connecting said conductor and plug and including an adjustable member having a pointed end to penetrate into the core of the conductor and receive ignition current therefrom.

6. In a radio shield for a spark plug, a metal shell having alateral extension, a body of dielectric material within said shell and removable therefrom at will, a portion of said dielectric body aligning with said lateral extension of the shel being apertured to receive a con ductor, and metallic contact means for electrically connecting said conductor and plug and including one part to physically engage the conductor and receive ignition current therefrom, and a second part gripping the conductor to hold it against axial displacement, said second part also acting to transmit to the spark plug the current received by the first part.

EDWARD B. NOWOSIELSKI. 

